Hi guys>>

I managed to build the circuit that is attached here. It is to control a fan motor.

the output voltage should go to power op-amp LM759. But I don't have this one.

So could someone please build a simple circuit to replace this op-amp.

It is a DC-fan with 12V.

 

I'm sorry but an operational amplifier is not a simple circuit to replace. That said, you should be able to substitute another type for the LM759. Tell us what opamps you have available to you and we'll help you pick one. There is no sense in using parts that are pure unobtainium.

Edit: Never mind, I see the problem is that the part was discontinued almost a decade ago.
Would an LM675 work for you? You would only need it for the last stage, not for the rest of the circuit.

 

Thanks Papabravo for replying.
In fact am tring to use power transistor instead of the power op-amp.
I used a power transistor 2N3055 and it is just about to work.